Dry-Type transformers

With over 100 years of experience, we provide high quality Dry-type transformers customized to your unique requirements. All dry-type transformers are self-cooled (AA) and made of stainless steel hardware, silicon steel core, and aluminum windings. 

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Types of Dry-Type Transformers

Dry-type transformers are a type of transformer that doesn’t use insulating liquids, unlike transformers where windings or cores are submerged in such liquids. Instead, these transformers encase their windings and cores in a sealed tank filled with pressurized air. Even without liquid insulation, they maintain a high level of safety.

Ventilated Dry-Type Transformers

Ventilated dry-type transformers utilize air circulation for cooling purposes. They feature openings or vents that allow natural air convection to dissipate heat generated during operation. This design enhances efficiency and ensures effective cooling without the need for additional cooling systems.

General purpose vented transformers

Ventilated transformers designed for general purposes find widespread use in commercial and light industrial applications, available in both single- and three-phase configurations. These transformers typically come in sizes ranging from 15 to 1000 kVA, featuring primary voltages between 380 and 575 V, and secondary voltages spanning 120 to 240 V. The coils are wound with either aluminum or copper conductors and utilize insulation materials with a rating of 220°C. Operating within a temperature rise range of 80°C to 150°C, these transformers function at a frequency of either 50 or 60 Hz.


Specifically engineered to resist the detrimental overheating effects caused by harmonics from nonlinear loads, K-factor transformers cater to equipment like computers, laser printers, copiers, and other office electronics. K-factor transformers also have cores and coils designed for lower induction levels, minimizing stray losses. While they don’t reduce harmonic levels, K-factor transformers are built to withstand the harmful heating effects of harmonic currents produced by nonlinear loads. Noteworthy features include oversized (200% rated) neutrals and electrostatic shielding.

Low Noise

When it comes to dry type transformers inside buildings, the focus on reduced noise levels becomes particularly important. Opting for low-noise transformers is a smart move in this context. These transformers, with their minimized vibrations in the magnetic steel core, maintain a humming sound 3dB lower than NEMA/ANSI standards. However, the impact of installation on noise levels should not be underestimated, especially in confined spaces like closets and corners, which can act as amplifiers. To truly enjoy the benefits of these quiet transformers, it’s crucial to adhere to acoustical principles and follow proper installation procedures within indoor environments.

Harmonic mitigated transformers

Nonlinear loads can lead to excess heating, potentially overloading transformers, generators, and conductors due to harmonic currents. Harmonic mitigation transformers, when strategically incorporated into an electrical system, effectively neutralize these harmonic currents. This ensures that the loads operate as intended by the manufacturer and maintains the electrical systems free from voltage distortion. These transformers are particularly beneficial for installations with a prevalence of harmonic loads, including educational facilities (K–12 and universities), government buildings, commercial offices, medical facilities, and call centers.

Encapsulated Dry-Type Transformers

In encapsulated dry-type transformers, the windings and core are enclosed in a solid, resin compound. This encapsulation not only provides insulation but also protects the transformer from environmental factors such as moisture and dust. This design offers a compact and robust solution suitable for various applications.

General purpose encapsulated transformers

General purpose encapsulated transformers are designed with versatility in mind, serving common roles in industrial applications. The single- and three-phase transformers are of the two-winding type, encapsulated (potted) in a mix of epoxy-coated sand and gravel. Ranging from 0.05 to 75 kVA, they operate across primary voltages of 380-575 V and secondary voltages of 120-240 V. Operating temperatures range from 115°C to 80°C at a frequency of 60 or 50 Hz. Enclosures are typically NEMA rated Type 3R or 4X, emphasizing their design for environmental resilience and protection.

Buck Boost transformers

Buck-boost transformers find their niche in scenarios requiring a subtle adjustment of available voltage—either a slight boost or reduction. When configured as autotransformers, they automatically handle this voltage adjustment. These single-phase encapsulated transformers come in three voltage combinations:
  1. 120 V x 240–12/24 V
  2. 120 V x 240–16/32 V
  3. 240 x 480 V–24/48 V
To achieve the desired voltage level and meet the load kVA requirement, specific combinations of these transformers are employed. Despite their small size, ranging from 0.05 kVA to 7.5 kVA, buck-boost transformers, wired as autotransformers, can efficiently handle voltage adjustments for loads extending to several hundred kVA.

Mini-power center transformers

Mini-power centers reduce cost, footprint, and installation issues by integrating an encapsulated transformer, interior, primary, and secondary main circuit breakers into a unified assembly. Ranging from 3 to 30 kVA, these transformers operate at primary voltages between 380 and 575 V, with secondary voltages of 120/240 V (single-phase) or 120/208 V (three-phase). Tailored for scenarios demanding 120 volts in distant settings like parking lots, workbenches, and temporary construction sites, these solutions offer efficiency in a compact design.

Non-Ventilated Dry-Type Transformers

Non-ventilated dry-type transformers, as the name suggests, operate without relying on external air circulation. They are enclosed in a sealed housing without vents. Instead, they use internal cooling systems, such fans or heat sinks, to dissipate heat. This design is advantageous in environments where external air circulation is limited or undesirable.

Totally enclosed non-ventilated transformers

Transformers that are completely enclosed and non-ventilated are well-suited for environments containing materials that could harm or obstruct traditional transformers. These could include conductive, corrosive, or combustible substances, as well as lint and dust that might block ventilation passages. Without any openings, heat dissipation occurs through the enclosure’s surface area. Typically ranging from 15 to 300 kVA, these transformers handle primary voltages between 380 and 575 V and secondary voltages from 120 to 240 V. Operating within a temperature rise range of 150°C to 80°C and at a frequency of 60 or 50 Hz, most of these transformers feature enclosures with NEMA ratings of Type 3R, 4X, or 12 for enhanced protection.